کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
6436018 | 1637534 | 2016 | 10 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: High-precision measurement and standard calibration of triple oxygen isotopic compositions (δ18O, Îâ²17O) of sulfate by F2 laser fluorination High-precision measurement and standard calibration of triple oxygen isotopic compositions (δ18O, Îâ²17O) of sulfate by F2 laser fluorination](/preview/png/6436018.png)
A new approach for measuring the triple oxygen isotope composition of sulfate minerals was developed using fluorine gas and an infrared laser to generate O2. A correction for the mass-dependent isotope effect observed during barite fluorination was rigorously calibrated. Analyte gas purification was performed via numerous cryofocus steps and the introduction of an in-line gas chromatograph. As with previous methods, our fluorination technique still requires pairing with independent δ18O measurements made by TC/EA conversion to carbon monoxide, but leads to higher yields than BrF5-based methods. We first calibrated our method against known silicate standards (UWG-2, SCO, NBS-28). Following from this, we report high-precision triple oxygen isotope ratios for international sulfate standards (IAEA-SO-5, IAEA-S O-6, NBS-127), and an internal laboratory standard, JMG. Replicate analyses of JMG yielded a Îâ²17O value of  â0.057 ± 0.004â° (standard error), demonstrating per-meg level precision that approaches instrumental limits. We provide δ17O and δ18O values that can be translated into any preferred reference frame for comparison with gases, water, or rocks/minerals. Quantification of differences in triple oxygen isotope composition of the standard reference materials further enables application of this measure and approach on environmental and geological materials.
Journal: Chemical Geology - Volume 440, 15 November 2016, Pages 50-59